2

Layer 3 Cisco Switch can also been used as Layer 2 only.

Is there any specific configuration in Cisco switch to verify this?

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  • 1
    Layer-3 switches are first and primarily layer-2 switches. For Cisco, unless you configure layer-3 features (SVIs, no switchport, IP addresses, etc.), the switch interfaces will all be layer-2 interfaces.
    – Ron Maupin
    Nov 10 '20 at 23:41
  • 1
    @RonMaupin On some switches, the default is routed ports. The Catalyst 6807-XL comes to mind... Nov 11 '20 at 0:00
5

Most (smaller) switches are layer-2 first, layer-3 second. So the default configuration is all layer-2. On those devices, the indicators that it's doing any layer-3 work is:

  • IP Routing is enabled (ip routing, ip unicast routing, etc.)
  • VLAN SVI's are configured with layer-3 address(es).
  • layer-2 interfaces have been put in layer-3 mode (no switchport)

Some of the bigger iron defaults to routed ports. They function much more like a router. For example the ages old 2948G-L3 -- the -L3 is very important. From the outside it looks just like any other 2948G (layer-2) switch, however it has a second system board (FXP1000) that turns it into a router. From the CLI, it can be hard to spot. But once configured, it'll be rather obvious:

  • No switchport configurations anywhere
  • layer-2 groups will be configured by bridge-groups
3

Cisco layer3 switch works in both layer3 and layer2 of OSI model .

Additional features of layer 3 switch compared to layer2 switch was ..

  1. routing can be configured
  2. switch virtual interfàce (SVI) can be configured
  3. DHCP configuration
  4. L3 interfàce can be configured on layer3 switch interfàce s
  5. inter-Vlan can be configured

Layer3 switch is compatible to switching & routing

Whereas layer2 switch is limited to only switching

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